Semi-gloss powder coating compositions

ABSTRACT

The present invention relates to powdered thermosetting compositions comprising as binder a co-reactable particulate mixture of a carboxyl group containing amorphous polyester, a glycidyl group containing acrylic copolymer and a curing agent having functional groups, reactable with the polyester’ carboxyl groups. The invention also relates to the use of said compositions for the preparation of powdered paints and varnishes which give semi gloss coatings with an adjustable gloss, providing an outstanding flow, excellent mechanical properties, good solvent resistance and weathering.

The present invention relates to powdered thermosetting compositionscomprising as binder a co-reactable particulate mixture of a carboxylgroup containing amorphous polyester, a glycidyl group containingacrylic copolymer and a curing agent having functional groups, reactablewith the polyester’ carboxyl groups. The invention also relates to theuse of said compositions for the preparation of powdered paints andvarnishes which give semi gloss coatings with an adjustable gloss,providing an outstanding flow, excellent mechanical properties, goodsolvent resistance and weathering.

At the present time, powdered thermosetting compositions are widely usedfor coating the most various articles. Today the majority of thesecoating compositions provide coatings having a high gloss after fusionand curing which is in fact very often equal to or even greater than90%.

There is an increasing demand for powdered paints and varnishes whichprovide coatings of good quality and with a reduced gloss, for examplefor coating certain accessories in the automotive industry, such aswheel rims, bumpers and the like, or for coating metal panels and beamsused in construction.

Various methods for manufacturing powdered paints and varnishes thatprovide matt coatings have been proposed.

According to one of these methods, powder coating compositionscomprising as a binder a co-reactable mixture of a carboxyl groupcontaining amorphous polyester and a glycidyl group containing acryliccopolymer are proposed and disclosed in a number of patents.

For instance, U.S. Pat. No. 5,436,311 describes a low gloss powderthermosetting composition comprising as a binder a mixture of a linearcarboxyl group containing polyester and a glycidyl group containingacrylic copolymer. The polyester has an acid number of 20 to 50 mgKOH/g. The acrylic copolymer has a number average molecular weight offrom 4000 to 10000 and is obtained from 5 to 30% by weight glycidyiacrylate or glycidyl methacrylate and 70 to 95% by weight of methylmethacrylate whereby up to 25% by weight of the methyl methacrylate canbe replaced by another vinyl monomer.

U.S. Pat. No. 5.407,706 describes a powder composition that provides lowgloss upon curing. The composition comprises (A) a resin comprising from10 to 90% weight of an acrylic resin having a viscosity of 100 to 800poises at 140° C. that is obtained by polymerising 10 to 50% weight ofglycidyl acrylate or glycidyl methacrylate with 90 to 50% weight of acopolymerisable monomer and 90 to 10% weight of a further acrylic resinhaving a viscosity of 1000 to 5000 poises at 140° C. that is preparedfrom defined comonomers, and (B) a polybasic acid compound having aviscosity of 100 to 2000 poises at 140° C. The equivalent ratio of theglycidyl groups to the acid groups of the polybasic acid compound may befrom 1.5 to 0.5.

U.S. Pat. No. 5,744,522 describes a powder coating composition having a60° gloss of less than about 60 which contains (A) a glycidyl groupcontaining acrylic copolymer having a weight average molecular weight offrom 2000 to 20000, (B) an aromatic carboxylic acid group containingpolyester with an acid number of from 10 to 300 mg KOH/g and (C) aparticular isocyanurate curing agent having carboxyl groups orderivatives thereof.

U.S. Pat. No. 6,310,139 deals with burnish resistant low gloss powdercoating compositions comprising (A) a polyester having hydroxyl andcarboxyl groups characterised by an acid and hydroxyl number of from 10to 30 mg KOH/g, and a glass transition temperature of less than 55° C.,(B) a glycidyl group containing acrylic copolymer having a numberaverage molecular weight greater than 8000 and (C) a blocked isocyanatederivative for reacting with the hydroxyl groups of the polyester resin.

Despite the existing variability of these binder systems, the coatingsderived all are subject to one or more disadvantages or shortcomings,mainly attributed to flexibility, gloss level or reproducibility.

Till now, powder coating compositions comprising as a binder a mixtureof a glycidyl group containing acrylic copolymer and a carboxylic acidgroup containing amorphous polyester, whether or not in combination witha additional curing agent, allow for “dead matt” characteristics, whichis indicated by a gloss as measured at a geometry of 60° according tothe ASTM D523 standard of from 0 to 10%.

When higher gloss levels are aimed for, the mixture of differentglycidyl group containing acrylic copolymers is suggested. as forexample in U.S. Pat. No. 5,407,706 or U.S. Pat. No. 5,744,522,nevertheless not without the typical drawbacks such as glossreproducibility.

It now has been surprisingly found that by using as a binder aco-reactable particular mixture of a carboxyl group containing amorphouspolyester and a glycidyl group containing acrylic copolymer along with astoechiometric excess of a curing agent having functional groupsreactable with the polyesters' carboxylic acid groups, it is possible toobtain powdered thermosetting compositions which produce coatings with areduced gloss in a reliable and reproducible way, along with goodflexibility and solvent resistance. Moreover it has been observed that avariation of the stoechiometric excess of the reactive groups of thecuring agent relative to the glycidyl groups of the acrylic copolymer,allows for an adjustable gloss level between about 10 and 70 as measuredat a geometry of 60° according to the ASTM D523 standard in areproducible way.

Thus, according to the present invention there are provided newthermosetting coating compositions comprising as binder a mixture of acarboxyl group containing polyester, a glycidyl group containing acryliccopolymer and a curing agent having functional groups reactable with thepolyester carboxylic acid groups, characterised in that 100 parts byweight of this binder comprises:

-   -   40.0 to 90.0 parts by weight of a carboxyl functional polyester        consisting of a carboxyl functional amorphous polyester composed        of from 50 to 100% mole of terephthalic acid and from 50 to 0%        mole of one or more aliphatic, cycloaliphatic or aromatic        polyacid other than terephthalic acid , referring to the        polyacid constituents, and of from 50 to 100% mole of neopentyl        glycol or 2-butyl-2-ethyl-1,3-propanediol or their mixtures and        from 0 to 50% mole of another aliphatic and/or cycloaliphatic        polyol, referring to the polyol constituents;    -   10.0 to 60.0 parts by weight of a glycidyl group containing        acrylic copolymer having a number average molecular weight of at        least 5000 and composed of 10 to 90% mole of a glycidyl group        containing monomer and from 90 to 10% mole of other monomers        copolymerisable with the glycidyl group containing monomers; and    -   0.5 to 15.0 parts by weight of a curing agent having functional        groups reactable with the polyester's carboxylic acid groups.

At the contrary of EP 00128097, the compositions of the presentinvention do not contain a carboxyl group containing semi-crystallinepolyester.

The carboxyl functional amorphous polyesters of the present inventiongenerally have an acid number from 15 to 100 mg KOH/g and preferablyfrom 30 to 70 mg KOH/g.

Preferably, the carboxyl functional amorphous polyesters further arecharacterised by:

-   -   number averaged molecular weight ranging from 1100 to 15000 and        more preferably from 1600 to 8500, measured by gel permeation        chromatography (GPC);    -   a glass transition temperature (Tg) from 40 to 80° C., measured        by Differential Scanning Calorimetry according to ASTM D3418        with a heating gradient of 20° C. per minute;    -   an ICI (cone/plate) viscosity accordingly to ASTM D4287,        measured at 200° C. ranging from 5 to 15000 mPa.s.

The polyacid constituent of the amorphous polyester, according to thepresent invention, is for 50 to 100% mole, preferably for 50 to 90%mole, composed of terephthalic acid, and for 0 to 50% mole, preferablyfor 10 to 50% mole, of another constituent selected from one or morealiphatic, cycloaliphatic or aromatic polyacids, such as isophthalicacid, fumaric acid, maleic acid, phthalic anhydride,1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid,1,2-cyclohexanedicarboxylic acid, succinic acid, adipic acid, glutaricacid, pimelic acid, suberic acid, azealic acid, sebacic acid, 1,12-dodecanedioic acid, trimellitic acid or pyromellitic acid, etc., orthe corresponding anhydrides.

According to a first embodiment of the invention, the polyacidconstituent of the amorphous polyester more preferably comprises from 50to 90% mole % of terephtalic acid or isophthalic acid or their mixturesand from 50 to 10% mole of an aliphatic, cycloaliphatic or aromaticpolyacid other than terephtalic acid or isophthalic acid. According toanother embodiment of the invention, the polyacid constituent of theamorphous polyester more preferably comprises from 50 to 90% mole % ofterephtalic acid and from 10 to 50% mole of an aliphatic, cycloaliphaticor aromatic polyacid other than terephtalic acid or isophthalic acid. Inthis case, the other polyacid is more preferably selected from adipicacid and trimellitic acid, and their mixtures.

According to yet another embodiment of the invention, the polyacidconstituent of the amorphous polyester more preferably comprises from 50to 90% mole % of terephtalic acid, from 2 to 30% mole of isophthalicacid and from 2 to 30% mole of an aliphatic, cycloaliphatic or aromaticpolyacid other than terephtalic acid or isophthalic acid. In this case,the other polyacid is more preferably adipic acid.

The glycol constituent of the amorphous polyester, according to thepresent invention, is for 50 to 100% mole composed of neopentyl glycolor 2-butyl-2-ethyl-1,3-propanediol or their mixtures and for 0 to 50%mole of another polyol constituent selected from one or more aliphaticand/or cycloaliphatic polyols, preferably selected from ethylene glycol,propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanediol,1,4-cyclohexanedimethanol, 2-methyl-1,3-propanediol,2-butyl-2-ethyl-1,3-propanediol, hydrogenated Bisphenol A,hydroxypivalate of neopentyl glycol, trimethylolpropane,ditrimethylolpropane, pentaërythrytol.

The carboxylic acid group containing amorphous polyesters, according tothe present invention, may be prepared using conventional esterificationtechniques well known in the art. The polyesters may be preparedaccording to a procedure consisting of one or more reaction steps.

For the preparation of these polyesters, a conventional reactor equippedwith a stirrer, an inert gas (nitrogen) inlet, a thermocouple, adistillation column connected to a water-cooled condenser, a waterseparator and a vacuum connection tube may be used.

The esterification conditions used to prepare the polyesters generallyare conventional, namely a standard esterification catalyst, such asdibutyltin oxide, dibutyltin dilaurate, n-butyltin trioctoate, sulphuricacid or a sulphonic acid, can be used in an amount from 0.05 to 1.50% byweight of the reactants and optionally, colour stabilisers, for example,phenolic antioxidants such as Irganox 1010 (Ciba) or phosphonite- andphosphite-type stabilisers such as tributylphosphite, can be added in anamount from 0 to 1% by weight of the reactants.

Polyesterification is generally carried out at a temperature which isgradually increased from 130° C. to about 190 to 250° C., first undernormal pressure, then, when necessary, under reduced pressure at the endof each process step, while maintaining these operating conditions untila polyester is obtained, which has the desired hydroxyl and/or acidnumber. The degree of esterification can be followed by determining theamount of water formed in the course of the reaction and the propertiesof the obtained polyester, for example the hydroxyl number, the acidnumber, the molecular weight or the viscosity.

When polyesterification is complete, cross-linking catalysts canoptionally be added to the polyester while it is still in the moltenstate. These catalysts are added in order to accelerate cross-linking ofthe thermosetting powder composition during curing. Examples of suchcatalysts include amines (e.g. 2-phenylimidazoline), phosphines (e.g.triphenylphosphine), ammonium salts (e.g. tetrabutylammonium bromide ortetrapropylammonium chloride), phosphonium salts (e.g.ethyltriphenylphosphonium bromide or tetrapropylphosphonium chloride).These catalysts are preferably used in an amount of 0 to 5% with respectof the weight of the polyester.

The glycidyl group containing acrylic copolymers of the presentinvention generally have an epoxy equivalent weight of 0.3 to 6.0 andpreferably from 1.0 to 4.0 milliequivalents of epoxy/gram of polymer.

Preferably, the glycidyl group containing acrylic copolymers are furthercharacterised by:

-   -   a number averaged molecular weight ranging from 5000 to 25000        and more preferably from 10000 to 20000;    -   a glass transition temperature (Tg) from 40 to 85° C., measured        by Differential Scanning Calorimetry (DSC), according to ASTM        D3418 with a heating gradient of 20° C. per minute;    -   an ICI (cone/plate) viscosity determined by the ICI method at        200° C. ranging from 60 to 50000 mPa.s;

The glycidyl group containing monomer used in the acrylic copolymer ofthe present invention is used in mole percentages ranging from 10 to 90and is preferably selected from, for example. glycidyl acrylate,glycidyl methacrylate, methyl glycidyl methacrylate, methyl glycidylacrylate, 3,4-epoxycyclohexylmethyl(meth)acrylate and acrylic glycidylether. They can be used singly or in combination of two or more.

The other monomers copolymerisable with the glycidyl group containingmonomer are used in mole percentages ranging from 10 to 90 and arepreferably selected from:

-   -   40 to 100 mole percentage of acrylic or methacrylic ester        monomers such as methyl acrylate, ethyl acrylate, n-propyl        acrylate, isopropyl acrylate, n-butyl acrylate, n-decyl        acrylate, methyl methacrylate, ethyl methacrylate, n-propyl        methacrylate, isopropyl methacrylate, n-butyl methacrylate,        isobutyl methacrylate, n-amyl methacrylate, n-hexyl        methacrylate, isoamyl methacrylate, allyl methacrylate,        sec-butyl methacrylate, tert-butyl methacrylate, 2-ethylbutyl        methacrylate, cinnamyl methacrylate, crotyl methacrylate,        cyclohexyl methacrylate, cyclopentyl methacrylate, methallyl        methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate,        2-phenylethyl methacrylate and phenyl methacrylate, and their        mixtures.    -   0 to 60 mole percentage of other ethylenically unsaturated        copolymerisable monomers such as styrene, alkyl-substituted        styrenes and chloro-substituted styrenes, acrylonitrile, vinyl        chloride and vinylidene fluoride and vinyl acetate, and their        mixtures.

The glycidyl group containing acrylic copolymer may be prepared byconventional polymerisation techniques, either in mass, in emulsion, orin solution in an organic solvent. The nature of the solvent is verylittle of importance, provided that it is inert and that it readilydissolves the monomers and the synthesised copolymer. Suitable solventsinclude toluene, ethyl acetate, butyl acetate, xylene, etc. The monomersare usually copolymerised in the presence of a free radicalpolymerisation initiator (benzoyl peroxide, dibutyl peroxide,azo-bis-isobutyronitrile, and the like) in an amount representing 0.1 to4.0% by weight of the monomers.

To achieve a good control of the molecular weight and its distribution,a chain transfer agent, preferably of the mercaptan type, such asn-dodecylmercaptan, t-dodecanethiol, iso-octylmercaptan, or of thecarbon halide type, such as carbon tetrabromide, bromotrichloromethane,etc., may also added in the course of the reaction. The chain transferagent is generally used in amounts of up to 10% by weight of themonomers used in the copolymerisation.

A cylindrical, double walled reactor equipped with a stirrer, acondenser, an inert gas (nitrogen, for example) inlet and outlet, andmetering pump feed systems is generally used to prepare the glycidylgroup containing acrylic copolymer.

Polymerisation generally is carried out under conventional conditions.Thus, when polymerisation Is carried out in solution, for example, anorganic solvent is introduced into the reactor and heated to refluxtemperature under an inert gas atmosphere (nitrogen, carbon dioxide, andthe like) and a homogeneous mixture of the required monomers, freeradical polymerisation initiator and chain transfer agent, when needed,is then added to the solvent gradually over several hours. The reactionmixture is then maintained at the indicated temperature for some hours,while stirring. The copolymer obtained is subsequently freed from thesolvent in vacuo.

The curing agent having functional groups reactable with the polyesters'carboxyl groups is preferably selected from a polyepoxy compound and/ora β-hydroxyalkylamide containing compound.

The polyepoxy compound, which is generally solid at room temperature,contains at least two epoxy groups per molecule such as for example,triglycidyl isocyanurate (TGIC) like the one marketed under thetradename of Araldite PT810 or the mixture of diglycidyl terephthalateand triglycidyl trimellitate, like the one marketed under the tradenameof Araldite PT910 or PT912.

The β-hydroxyalkylamide containing compound preferably answers thegeneral structure as represented in Formula 1.

Wherein:

-   -   A represents a mono- or polyvalent organic group derived from a        saturated or unsaturated alkyl group with 1 to 60 carbon atoms        (for example ethyl, methyl, propyl, butyl, pentyl, hexyl,        heptyl, octyl, nonyl, decyl, eicosyl, triacontyl, tetracontyl,        pentacontyl and hexacontyl); an aryl group (such as phenyl,        naphtyl); a trialkene amino group with 1 to 4 carbon atoms per        alkylene group (for example trimethylene amino and triethylene        amino); or an unsaturated radical containing one or more alkenic        groups (—C═C—) with 1 to 4 carbon atoms (such as ethenyl,        1-methyl ethenyl, 3-butenyl-1,3-diyl and 2-propenyl-1,2-diyl),        carboxy-alkenyl group with 1 to 4 carbon atoms (for example        3-carboxy-2-propenyl), alkoxy carbonyl alkenyl with 1 to 4        carbon atoms (such as 3-methoxy carbonyl-2-propenyl)    -   R¹ represents hydrogen, an alkyl group with 1 to 5 carbon atoms        or a hydroxyalkyl group with 1 to 5 carbon atoms    -   R² and R³ are the same or different and each independently        represents hydrogen or a straight or branched alkyl group with 1        to 5 carbon atoms, while one of the groups R² and one of the        groups R³ may also form, together with the adjacent carbon        atoms, a cycloalkyl group.    -   n and m, independently, have values from 1 to 2, preferably from        1.6 to 2.        A is preferably an C1-C10 alkyl.

In a preferred embodiment of the present invention, the curing agent,having functional groups reactable with the polyesters' carboxylic acidgroups, is a β-hydroxyalkylamide according to Formula II

wherein n is from 0.2 to 1, R¹ is selected from hydrogen and alkylgroups with 1 to 5 carbon atoms and R³ is hydrogen (Primid XL552 fromEMS) or a methyl group (Primid QM1260 from EMS).

The thermosetting powdered composition of the present invention,preferably comprises a binder which, for 100 parts by weight of binder,consists of:

-   -   40.0 to 90.0, preferably 60.0 to 80.0, parts by weight of the        carboxyl functionalised amorphous polyester;    -   10.0 to 60.0, preferably 20.0 to 50.0, parts by weight of the        glycidyl group containing acrylic copolymer; and    -   0.5 to 15.0. preferably 2.3 to 12.0, parts by weight of the        curing agent.

In addition to the essential binder components described above,compositions within the scope of the present invention can also includeone or more flow control agents such as Resiflow PV5 (Worlee), Modaflow(Monsanto), Acronal 4F (BASF), etc., one or more degassing agents suchas benzoin (BASF) etc. and one or more fillers. To the formulation, oneor more UV-light absorbers such as Tinuvin 900 (Ciba), hindered aminelight stabilisers represented by Tinuvin 144 (Ciba), other stabilisingagents such as Tinuvin 312 and 1130 (Ciba), antioxidants such as Irganox1010 (Ciba) and stabilisers from the phosphonite or phosphite type canbe added.

Both, pigmented systems as well as clear lacquers can be prepared.

A variety of dyes and pigments can be utilised in the composition ofthis invention. Examples of useful pigments and dyes are: metallicoxides such as titaniumdioxide, ironoxide, zincoxide and the like, metalhydroxides, metal powders, sulphides, sulphates, carbonates, silicatessuch as ammoniumsilicate, carbon black, talc, china clay, barytes, ironblues, leadblues, organic reds, organic maroons and the like.

The components of the composition according to the invention may bemixed by dry blending in a mixer or blender (e.g. drum mixer). Thepremix is then homogenised at temperatures ranging from 70 to 150° C. ina single screw extruder such as the BUSS-Ko-Kneter or a double screwextruder such as the PRISM or APV. The extrudate, when cooled down, isground to a powder with a particle size ranging from 10 to 150 μm. Thepowdered composition may be deposed on the substrate by use of a powdergun such as an electrostatic CORONA or a friction charging TRIBO spraygun. On the other hand well-known methods of powder deposition such asthe fluidised bed technique can be used. After deposition the powder isheated to a temperature between 160 and 220° C., causing the particlesto flow and fuse together to form a smooth, uniform, continuous,uncratered coating on the substrate surface.

The thermosetting powder composition according to the present inventionmay be used as a coating for metallic and non-metallic surfaces.

Entirely or partially coated substrates wherein the coating materialused is a thermosetting powder coating composition according toinvention are also an object of the present invention.

The following examples are submitted for a better understanding of theinvention without being restricted thereto.

EXAMPLE 1 Synthesis of a Carboxylic Acid Group Containing AmorphousPolyester

422.30 parts of neopentyl glycol is placed in a conventional four neckround bottom flask equipped with a stirrer, a distillation columnconnected to a water cooled condenser, an inlet for nitrogen and athermometer attached to a thermoregulator.

The flask contents are heated, while stirring under nitrogen, to atemperature of circa 140° C. at which point 573.15 parts of terephthalicacid. 30.17 parts of adipic acid and 1.25 parts of n-butyltintrioctoateare added. The reaction is continued at 240° C. under atmosphericpressure until about 95% of the theoretical amount of water is distilledand a transparent hydroxyl functionalised prepolymer with followingcharacteristics is obtained:

-   -   AN=7.6 mg KOH/g    -   OHN=56.6 mg KOH/g    -   ICI^(175° C.) (Cone/Plate)=2200 mPa.s

To the first step prepolymer standing at 200° C., 110.14 parts ofisophthalic acid is added. Thereupon, the mixture is gradually heated to230° C. After a 2 hour period at 230° C. and when the reaction mixtureis transparent, 1.0 part of tributylphosphite and 1.0 part ofn-butyltintrioctoate is added and a vacuum of 50 mm Hg is graduallyapplied. After 3 hours at 230° C. and 50 mm Hg, followingcharacteristics are obtained:

-   -   AN=35.5 mg KOH/g    -   OHN=2.5 mg KOH/g    -   ICI^(200° C.) (Cone/Plate)=5000 mPa.s

The carboxyl functionalised polyester is cooled down to 180° C. and theresin is discharged.

Accordingly the procedure as described in example 1 the polyesters ofexamples 2 to 8, answering the composition as in table 1, are prepared.TABLE 1 Ex. 5 Ex. 2 Ex. 3 Ex. 4 (*) (*) Ex. 6 Ex. 7 Ex. 8 Step 1neopentyl glycol 431.0 378.1 411.8  342.8  422.9 417.9 421.1ethyleneglycol  18.0 trimethylolpropane 30.9 13.9 isophthalic acid 36.9 50.2  60.2 terephthalic acid 632.6 548.2 537.3  452.0  541.5 637.3606.1 adipic acid 59.7  55.8 acid number, mg 12 11 3  16   3 6 7 KOH/ghydroxyl number, 51 68 42  40  58 45 55 mg KOH/g viscosity (175° C.)2990 3150 2940 1750 3000 6600 2500 Step 2 isophthalic acid 48.5 88.2118.2 adipic acid 28.8 50.7  71.2 81.0 trimellitic anhydride 119.5  81.2 46.2 acid number, mg 22 48 69  65  46 30 34 KOH/g hydroxyl number, 3 47   9   9 5 3 mg KOH/g viscosity (200° C.) 7500 5800 2980 6020** 9200**5600 4400 Mn 5600 2700 3200 2750 3450 5850 3200(*) For the preparation of the polyester of example 4 and 5, thereaction of trimellitic anhydride with the first step prepolymer is doneat 190° C. under atmospheric conditions. After two hours at 190° C. theresin is discharged.**at 175° C.

EXAMPLE 9 Preparation of the Glycidyl Group Containing Acrylic Copolymer

80 parts of n-butyl acetate are brought in a double walled flask of 51equipped with a stirrer, a water cooled condenser, an inlet for nitrogenand a thermocouple attached to a thermoregulator.

The flask content is then heated and stirred continuously while nitrogenis purged through the solvent. At a temperature of 125° C. a mixture of0.8 parts of tertbutylperoxybenzoate in 20 parts of n-butyl acetate arefed in the flask during 215 minutes with a peristaltic pump. 5 minutesafter this start another pump is started with the feeding of a mixtureof 22 parts of styrene, 24 parts of glycidyl methacrylate, 40 parts ofbutyl methacrylate and 14 parts of methyl methacrylate, during 180minutes. The synthesis takes 315 minutes.

After evaporation of the n-butyl acetate an acrylic copolymer withfollowing characteristics is obtained: ICI viscosity @200° C. 16000 mPa· s Mn 15000 Mw 38200

EXAMPLE 10 To 11

Accordingly the procedure as described in example 9, the acryliccopolymers of example 10 and example 11, answering the compositions asin table 2, were prepared. TABLE 2 example 10 example 11 styrene 12 22glycidyl methacrylate 24 24 butyl methacrylate 20 40 methyl methacrylate44 14 n-butyl peroxybenzoate 2.0 0.6 Mn 9300 22600 Mw 20400 52400ICI^(200° C.), mPa · s 11000 30000

EXAMPLE 12

The polyesters and acrylic copolymers as illustrated above, are thenformulated to a powder accordingly to the white paint formulation asgiven below. White paint formulation Binder 74.00 Kronos 2310 24.67Resiflow PV5 0.99 Benzoin 0.34

The powders are prepared first by dry blending of the differentcomponents and then by homogenisation in the melt using a PRISM 16 mmL/D 15/1 twin screw extruder at an extrusion temperature of 85° C. Thehomogenised mix is then cooled and ground in an Alpine UPZ100.Subsequently the powder is sieved to obtain a particle size between 10and 110 μm. The powder thus obtained is deposited on cold rolled steel,by electrostatic deposition using the GEMA—Volstatic PCG 1 spray gun. Ata film thickness between 50 and 80 μm the panels are transferred to anair-ventilated oven, where curing proceeds for 18 minutes at atemperature of 200° C.

The paint characteristics for the finished coatings obtained from thewhite powder formulation as given above, are reproduced in table 3(Example 13 to 25). TABLE 3 Poly- GMA- Curing Gloss Solvent esteracrylic agent 60° DI RI Resistance Ex. 13 Ex. 1 Ex. 9 XL552 10 200 200100 70.9 24.8 4.2 Ex. 14 Ex. 1 Ex. 9 XL552 20 200 200 120 69.5 24.3 6.2Ex. 15 Ex. 2 Ex. 9 XL552 55 160 160 120 78.6 18.3 3.1 Ex. 16 Ex. 4 Ex. 9XL552 25 160 160 100 53.0 43.3 3.7 Ex. 17 Ex. 4 Ex. 9 XL552 40 120 100120 49.4 40.4 10.2 Ex. 18 Ex. 1 Ex. 9 QM1260 40 100 100 100 71.0 24.84.2 Ex. 19 Ex. 1 Ex. 9 TGIC 45 160 180 120 70.2 24.6 5.2 Ex. 20 Ex. 1Ex. 10 XL552 68 200 200 120 72.4 25.4 2.2 Ex. 21 Ex. 3 Ex. 11 XL552 51200 200 140 61.3 35.7 3.0 Ex. 22 Ex. 5 Ex. 9 XL552 35 180 160 140 51.242.0 7.2 Ex. 23 Ex. 6 Ex. 9 XL552 20 200 200 120 60.0 36.0 4.0 Ex. 24Ex. 7 Ex. 9 XL552 25 200 200 100 69.5 24.3 6.2 Ex. 25 Ex. 8 Ex. 11 XL55240 200 200 120 71.0 25.0 4.0

In this table:

-   Column 1: indicates the identification number of the formulation-   Column 2: indicates the type and quantity in weight % of amorphous    polyester-   Column 3: indicates the type and quantity in weight % of acrylic    copolymer-   Column 4: indicates the type and quantity in weight % of curing    agent-   Column 5: indicates the 60° gloss, measured according to ASTM D523-   Column 6: indicates the direct impact strength according to ASTM    D2794. The highest impact which does not crack the coating is    recorded in kg.cm-   Column 7: indicates the reverse impact strength according to ASTM    D2794. The highest impact which does not crack the coating is    recorded in kg.cm-   Column 8: number of twofold rubbing movements (to and fro) with a    cotton pad impregnated with MEK which does not detrimentally affect    the appearance of the surface of the cured film

The coatings as obtained from the powder formulations of example 13 to25, all prove to have a nice smooth finish with an reproducible reducedgloss level.

Besides, good flexibility and solvent resistance, the finishes obtainedhave an outstanding resistance to burnishing i.e. they do not changegloss upon marring, scratching or rubbing.

1-12. (canceled)
 13. Thermosetting coating compositions comprising asbinder a mixture of a carboxyl group containing polyester, a glycidylgroup containing acrylic copolymer and a curing agent having functionalgroups reactable with the polyester carboxylic acid groups, wherein 100parts by weight of this binder comprises: 40.0 to 90.0 parts by weightof a carboxyl functional polyester consisting of a carboxyl functionalamorphous polyester composed of from 50 to 100% mole of terephthalicacid and from 50 to 0% mole of one or more aliphatic, cycloaliphatic oraromatic polyacid other than terephthalic acid, referring to thepolyacid constituents, and of from 50 to 100% mole of neopentyl glycolor 2-butyl-2-ethyl-1,3-propanediol or their mixtures and from 0 to 50%mole of another aliphatic and/or cycloaliphatic polyol, referring to thepolyol constituents; 10.0 to 60.0 parts by weight of a glycidyl groupcontaining acrylic copolymer having a number average molecular weight ofat least 5000 and composed of 10 to 90% mole of a glycidyl groupcontaining monomer and from 90 to 10% mole of other monomerscopolymerizable with the glycidyl group containing monomers; and 0.5 to15.0 parts by weight of a curing agent having functional groupsreactable with the polyester's carboxylic acid groups.
 14. Compositionaccording to claim 13, wherein the aliphatic, cycloaliphatic or aromaticpolyacid other than terephthalic acid is selected from the groupcomprising isophthalic acid, fumaric acid, maleic acid, phthalicanhydride, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylicacid, 1,2-cyclohexanedicarboxylic acid, succinic acid, adipic acid,glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid,1,12-dodecanedioic acid, trimellitic acid, pyromellitic acid, or thecorresponding anhydrides, and the other aliphatic or cycloaliphaticpolyol is selected from ethylene glycol, propylene glycol,1,4-butanediol, 1,6-hexanediol, 1,4-cyclohexanediol,1,4-cyclohexanedimethanol, 2-methyl-1,3-propanediol,2-butyl-2-ethyl-1,3-propanediol, hydrogenated Bisphenol A,hydroxypivalate of neopentyl glycol, trimethylolpropane,ditrimethylolpropane, pentaërythrytol.
 15. Composition according toclaim 13, wherein the polyacid constituent of the carboxyl functionalamorphous polyester comprises from 50 to 90% mole % of terephtalic acidor isophthalic acid or their mixtures and from 50 to 10% mole of analiphatic, cycloaliphatic or aromatic polyacid other than terephtalicacid or isophthalic acid.
 16. Composition according to claim 13, whereinthe polyacid constituent of the carboxyl functional amorphous polyestercomprises from 50 to 90% mole % of terephthalic acid and from 10 to 50%mole of an aliphatic, cycloaliphatic or aromatic polyacid other thanterephthalic acid or isophthalic acid.
 17. Composition according toclaim 13, wherein the polyacid constituent of the carboxyl functionalamorphous polyester comprises from 50 to 90% mole % of terephthalicacid, from 2 to 30% mole of isophthalic acid and from 2 to 30% mole ofan aliphatic, cycloaliphatic or aromatic polyacid other thanterephthalic acid or isophthalic acid.
 18. Composition according toclaim 13, wherein the carboxyl functional amorphous polyester hasfollowing properties: an acid number from 15 to 100 mg KOH/g andpreferably from 30 to 70 mg KOH/g; a number averaged molecular weightranging from 1100 to 15000 and a glass transition temperature (Tg) from40 to 80° C.; an ICI (cone/plate) viscosity at 200° C. ranging from 5 to15000 mPa.s.
 19. Composition according to claim 18 wherein the numberaveraged molecular weight is from 1600 to
 8500. 20. Compositionaccording to claim 13, wherein the glycidyl group containing monomer isselected from glycidyl acrylate, glycidyl methacrylate, methyl glycidylmethacrylate, methyl glycidyl acrylate, 3,4-epoxycyclohexylmethyl(meth)acrylate and acrylic glycidyl ether, used singly or in combinationof two or more, and the other monomers copolymerizable with the glycidylgroup containing monomers is selected from: 40 to 100 mole percentage ofacrylic or methacrylic ester monomers such as methyl acrylate, ethylacrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate,n-decyl acrylate, methyl methacrylate, ethyl methacrylate, n-propylmethacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutylmethacrylate, n-amyl methacrylate, n-hexyl methacrylate, isoamylmethacrylate, allyl methacrylate, sec-butyl methacrylate, tert-butylmethacrylate, 2-ethylbutyl methacrylate, cinnamyl methacrylate, crotylmethacrylate, cyclohexyl methacrylate, cyclopentyl methacrylate,methallyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate,2-phenylethyl methacrylate and phenyl methacrylate, and their mixtures;0 to 60 mole percentage of other ethylenically unsaturatedcopolymerisable monomers such as styrene, alkyl-substituted styrenes andchloro-substituted styrenes, acrylonitrile, vinyl chloride andvinylidene fluoride and vinyl acetate, and their mixtures. 21.Composition according to claim 13, wherein the glycidyl group containingacrylic copolymer has following properties: a number averaged molecularweight ranging from 5000 to 25000 a glass transition temperature (Tg)from 40 to 85° C., measured by Differential Scanning Calorimetry (DSC),according to ASTM D3418 with a heating gradient of 20° C. per minute anICI (cone/plate) viscosity determined by the ICI method at 200° C.ranging from 60 to 50000 mPa.s
 22. Composition according to claim 21wherein the number averaged molecular weight is from 10000 to
 20000. 23.Composition according to claim 13, wherein the curing agent is apolyexpoxy compound and/or a β-hydroxyalkylamide containing compound.24. Composition according claim 13, wherein the curing agent is aβ-hydroxyalkylamide according to Formula II

wherein n is from 0.2 to 1, R¹ is selected from hydrogen and alkylgroups with 1 to 5 carbon atoms and R³ is hydrogen or methyl. 25.Composition according to claim 13, which comprises a binder which, for100.0 parts by weight of binder, consists of 60.0 to 80.0 parts byweight of the carboxyl functionalized amorphous polyester; 20.0 to 50.0parts by weight of the glycidyl group containing acrylic copolymer; and2.3 to 12.0 parts by weight of a β-hydroxyalkylamide curing agent. 26.Composition according to claim 13 containing: one or more UV-lightabsorbers and/or hindered amine light stabilisers; one or more flowcontrol agent; one or more degassing agent; and/or one or more pigment,dye and/or filler.